- Growing veggies in containers
- Getting Started with Raised Beds
- THE PERFECT RAISED BED SOIL
- 40% SOIL
- 40% COMPOST
- 20% AERATION
- FILLING YOUR RAISED GARDEN BED
- What about Fertilizer?
- IMPROVING YOU EXISTING SOIL
- Calculate the Amount of Soil Needed
- 1. Core Gardening
- 2. Hugelkultur Raised Bed
- 3. Ruth Stout Garden Bed
- 4. Back to Eden Garden Bed
- Listen to the podcast
- My lasagne method
- Want my exact step by step recipe for filling a raised bed? Get it here.
- Topsoil 101
- Where Can I Buy Topsoil?
- Can I Use Topsoil in Containers?
- How do I Figure out how Much Topsoil I Need?
- Topsoil Myths & Misunderstandings
- improve your soil
- Topsoil calculator for raised beds: topsoil calculator metrics made easy
- how much soil i need for a 4×4 raised bed
Growing veggies in containers
Last updated on 5 August 2019
Always wanted to grow veggies but don’t have the space? Growing veggies in containers just might be the answer. Jane Warburton of Potager of Urban Garden Creations shows you how to use containers to turn a tiny courtyard into a kitchen garden in a weekend:
YOU’LL ALSO LOVE: Make a vertical garden from PVC pipes
What you’ll need:
- Wooden boxes that are at least 20cm deep; alternatively use baskets or containers with drainage holes. To give your wooden planters a longer lifespan, Jane advises that you waterproof the interior of the box using a non-toxic waterproofing product like SelfCoat Clear Guard and seal the wood on the outside with a non-toxic oil or water-based sealant.
- To make your own planter boxes, use lengths of cedar or meranti (pine will warp over time) and four aluminium brackets per planter. You’ll also need a drill, screws, a hammer and nails and landscaping fabric or shade cloth.
- A good soil mix.
- Edible plants. June’s a good time to plant perennial herbs such as lavender, rosemary and thyme plus lettuce seedlings, rocket, bok choy, baby spinach and mizuna. Add a few flowers; blooms like marigolds act as companion plants.
How to do it:
1. Make a planter box
“We made 1,2m x 80cm boxes with a depth of 22cm out of cedar and joined the four sides with aluminium brackets to hold them together,” explains Jane. “Cedar planks were nailed to the bottom of each box to form a base with gaps left between them for drainage. Additional planks, turned on their sides, act as ‘feet’ allowing the boxes to be raised off the ground.” Lastly, line the inside of the planters with the landscaping fabric or shade cloth to hold in the soil, but still allow water to drain through.
READ MORE: Make a stylish container veggie garden
2. Position your boxes
“Choose a spot close to your kitchen so that you can pop out and pick fresh ingredients when you’re cooking. Most herbs and veggies enjoy full sun, but in SA a full day of sun is generally too harsh for more tender plants like lettuce, so an area that is sunny for part of the day is best,” says Jane.
If you’re using more than one planter box, leave spaces between them so you can move them around when weeding and harvesting. Put the boxes in position before you fill them with soil.
3. Add soil
“A combination of compost and loam mixed with a bit of vermiculite (which helps with water retention) and peat moss is best for herbs and veggies,” says Jane. “Good garden mixes are available at most nurseries, but avoid potting soil, which is not suitable for vegetable seedlings.”
READ MORE: 10 Vegetables and herbs for small spaces
4. Plant them up
Once you’ve selected your seedlings, Jane advises that you arrange them in your container to ensure you’re happy with the overall composition before you start planting. Remember to position the largest plants at the back and to also take leaf texture, shape and colour into account to create an attractive look.
READ MORE: Container ideas
“You can plant herbs and veggies closer together in a container than you would in the ground. However, you’ll need to pick herbs regularly as this acts as natural pruning,” says Jane. “You can also add tripods to your containers and train plants like tomatoes, gem squash and beans up them to make the most of the available planting space.
“If you’re using single pots, it’s best to have one type of plant per pot, but in a larger planting box, companion planting is best,” Jane adds.
Urban Garden Creations 082 446 0445, or potager-garden.com
First things first, let’s set the record straight: “Dirt” is not soil! Soil is rich, full of nutrients, and is biologically active! In contrast, dirt is usually devoid of all these things. Soil improves with time and age, as the soil food web blossoms. It is a living, breathing, dynamic ecosystem of its own. Therefore, our goal here is not to simply fill our raised beds with soil, but to create an optimum living organic raised bed soil that plants love!
The Soil Food Web. Image Courtesy of Heidelberg Farms via Pinterest
I hate to say it… but no matter how much love, energy, or money you invest into your garden, if you have crummy soil, the result will be crummy plants. If you have gone through the effort to build or buy yourself some awesome raised garden beds, let’s get them filled up with the right stuff! However, the answer isn’t as simple as “go grab X brand of soil”. In my experience, not one soil, be it in bulk or bagged, is going to be perfect for growing vegetables on its own straight out of the bag.
Another thing I hate to say is the word “perfect”. I typically avoid using it because of the impossible expectations it implies. I’m going with it for this post, but know that the ideal soil can vary in its origins and composition, and yours may differ from ours! Think of creating the perfect soil as an art. There are many personal touches you can put on it. With that in mind, I am simply sharing the way we prefer to craft and build our organic living soil.
If you already have filled your raised garden beds with less-than-ideal soil, don’t fret! There are ways to amend and improve it. We’ll discuss that too.
Getting Started with Raised Beds
Looking for tips on how to build a raised bed? Check out this post to learn and see how we build our beds!
Not feeling up to building your own? That’s okay! There are some sort of flimsy kits out there, but there are also some really excellent, durable, beautiful cedar raised bed kits available too! These ones from Gardener’s Supply get great reviews. They come in a variety of sizes, and at 15″ deep, will provide a nice amount of root space for your plants.
Our newest raised garden bed. This is the bed we show being filled in this soil post below, and also what we showed building in the “How to Design & Build a Raised Garden Bed” post
THE PERFECT RAISED BED SOIL
“What kind of soil do you fill your raised garden beds with?” I get asked this question All. The Time! As I think we have already established, soil health and quality is everything when it comes to a bountiful, healthy, productive garden, so we don’t mess around here! Using a combination of quality organic soil, compost, and an aeration addition will create the “perfect” soil. By perfect, I mean soil that is rich, fertile, holds moisture, but also has good drainage and what I like to call “fluff” to it.
Our target recipe is to fill raised garden beds with a mixture of about 40% soil, 40% compost, 20% aeration – plus a few other goodies that we’ll discuss momentarily.
This is an approximate estimation, and doesn’t need to be exact… Also, all of the same principles we’ll cover in this post could easily be applied to container gardening, just scaled down. For example if you need to fill fabric grow bags, wine barrels, or pots.
Before you can go about choosing and purchasing soil, you’ll need first to calculate how much volume is needed to fill the raised garden bed(s) you have.
Bags of garden soil come in measurements of cubic feet, usually in a range of 1 to 3 cubic-foot bags. Bulk soil purchased from a local landscape supply company will be in cubic yards. First, calculate the volume of your bed in cubic feet. To do this, simply multiply the width by length by depth in feet (e.g. 4’ x 6’ x 1.5”).
Now you have your total cubic feet, and can figure out how much bagged soil it would take to fill the bed! If you choose to get some bulk soil too, you’ll need to calculate volume in cubic yards. To convert your amount to cubic yards, simply multiply your cubic foot number by 0.037037, or use this converter.
If math isn’t your strong suit (or you’re just feeling lazy…. no shame!) here is a raised bed soil calculator that will do it all for you, in both cubic feet or yards. Why didn’t I just give this to you in the first place? Because I am mean, and wanted you to exercise that brain a little.
Ta da! Now you have your volume needed.
Tip: If you calculated that you need several yards of soil for your project, you are not going to want to fill all your beds using only bagged soil, trust me… Look up local landscape supply companies and see what they have to offer in bulk! On the other hand, if you need to fill just one modest raised bed or two, purchasing bagged soil could be the way to go.
If we have several really deep, big beds to fill at once, we buy some organic soil and compost in bulk from a local landscape company and have it delivered. Bulk soil composition and type will vary depending on your location. Our local bulk soil is called “planters mix” and is comprised of 2 parts top soil, 1 part compost and 1 part soil conditioner. I have heard of other gardeners who enjoy using equal parts topsoil, composted manure, and sand purchased in bulk. In that recipe, the sand is serving as the “aeration” ingredient.
Bulk delivery of “planters mix” and an organic soil condition/compost blend for a large project. We’ll mix this with higher quality bagged materials too.
We never rely on bulk soil alone, since it doesn’t always seem to be the highest quality or our preferred texture. At least that is the case in our experience. Therefore, the bulk soil is added more as a space-filler at the bottom of very deep beds, like our 2-foot deep ones, up to about a quarter full.
For the remainder of the volume, we go for high-quality organic bagged soil blends, plus compost. We might continue to mix in a little bulk soil here and there to increase the volume, but not nearly as much as the other good stuff. For bagged soil, we usually turn to G&B Organics (by Kellogg) which is carried at our local Ace Hardware garden center and local Farm Supply. If we are doing a big shopping spree at Home Depot to buy lumber and other supplies, we’ll pick up some of their Kellogg Organics line of bagged soils.
We aren’t 100% loyal to Kellogg only, and this is not a sponsored post… I am simply sharing what works well in our garden! Their products are readily available, affordable, OMRI-certified for organic gardening, and create good results! Both G&B Organics and Kellogg offer big ole 3-cubic foot bags of raised bed planting mix and soil conditioner. Other great brand options are Dr. Earth’s, Roots Organics, E.B. Stone, or Fox Farm, to name a few.
You do not want “potting soil” only, as it is too light and fluffy for raised beds. In the photo below, you can see that we mix various types of bagged soil and conditioners. By combining a few different things, you’re getting a nice variety of composition and texture. Some are a little more woody, some more fluffy, some with perlite or pumice, some without.
Again, this bulk-bagged combo is mostly used for when we are filling many large beds at once. For instances where just one or two modest beds need to be filled, we’ll often go with all bagged material. For a smaller volume, we’ve found it isn’t worth the delivery fee or minimum order amount to get the bulk soil. Plus, the bagged stuff is often times superior in quality anyways.
Compost is organic matter that has been thoroughly broken down and decomposed into rich nutrient-dense plant food. It is a killer soil conditioner and will make your garden shine! We try to add as much homemade compost from our worm bin or our large compost pile as possible. However, we usually cannot make quite enough homemade compost to meet all of our needs, especially for large projects like filling raised beds. So we do end up supplementing with organic bagged compost or bulk compost too. The bulk compost option that we purchase is made from local green waste.
Our favorite bagged compost is Malibu Compost Biodynamic Blend, or just referred to as “Bu’s”. It is aged, composted cow manure from certified organic dairy farms. They use biodynamic practices. The compost ingredients include organic aged manure, straw, vineyard wood chips, plus yarrow, chamomile, valerian, stinging nettle, dandelion, and oak bark! It is not uncommon to rip open a bag to dozens of happy worms squirming around in there.
We love Bu’s. People hear me talking about this on Instagram and often think I am talking about how much we love “booze”… 😂
Unfortunately, Bu’s is primarily available on the West Coast. If you live in the Northeast, Coast of Maine makes a similar product. I’m sure there are many more companies out there, all over the U.S. Leave a comment if you are aware of a good local product like this in your area!
Manure versus Compost
Note that fresh manure is very different from compost. Yes, Bu’s starts with manure, but it aged and composted over time to become a more mild, balanced product. Fresh manure that hasn’t been properly aged is very high in nitrogen and can burn your plants. Therefore, avoid adding fresh animal manure to your garden. I am also a little leery of animal manures that are not from certified organic operations, or have an otherwise unknown source.
Aside from our homemade compost and Bu’s, we are able to get an “organic compost” product from our local landscape supply company in bulk for big projects. Check to see if your local companies sell something similar! We also consider some of the bagged products like G&B Organics “Harvest Supreme” as more of a compost amendment than a soil, so we take those into account when shooting for that 40/40/20 ratio.
Last but not least, worm castings (aka worm poop!) are compost too. Worm castings are so good for your plants, they’re referred to as “black gold”. I highly suggest you try starting a worm bin at home! It is a terrific way to divert food waste from the landfill, and up-cycle that “waste” into a incredibly valuable product for your garden or house plants! Worm bins are inexpensive, pretty easy to maintain, and no, they do not smell bad. Learn how to set up and maintain a super simple worm bin here!
A little tub of screened worm castings or “black gold” being added to the new raised bed, from our worm bin. As you can see, a few friends came along for the party!
If you aren’t up keeping your own worm bin, you could purchase finished worm castings and add a little to each bed. We can usually find bags of G&B Organics Worm Gro locally, or you could pick up some worm castings from Uncle Jim’s Worm Farm online!
To find premium bagged compost and soil, I suggest looking not only at your local garden center, but also your local hydroponic store or “grow shop” too! Those shops are usually geared towards growing cannabis, and carry some high quality products.
Nearly as important as the compost component, an aeration addition is key to healthy soil. This could include lava rock, pumice, or perlite. Coarse sand also promotes aeration and drainage, but not quite as effectively as the others.
Why add material for aeration? Well, as we talked about, soil is full of living things, and they need air to thrive! Those living things include beneficial microbes, nematodes, worms, protozoa, fungi, and more. Last but certainly not least, your plant’s roots need air to thrive too! They breathe through their roots! You’ll often hear me stress to not over-love your plants with too much water, effectively drowning them.
An aeration additive doesn’t only provide air. Their presence promotes drainage and prevents the soil from over-compacting. It may seem counter-intuitive, but absorbent materials like lava rock and pumice also increase moisture retention at the same time as providing good drainage. They’ll hold water within themselves, helping to maintain an evenly moist raised bed for a longer period of time between watering. Like many things in gardening, it’s all about balance.
Keep in Mind:
A lot of bagged soil mixes already contain some perlite, pumice, or rice hulls. Those are all forms of “aeration”, and are adding to our target total. So if you use primarily bagged mixes, read the ingredient list. If they contain those things, you can go lighter on adding additional aeration (e.g. perhaps only 10% extra, if any). However, if you buy only bulk soil and compost products that do not contain any aeration additive, you’ll want to add more. Make sense? Like I said, this doesn’t all need to be an exact science.
For the aeration portion of our soil recipe, we have come to love volcanic rock. It is also called lava cinders and is frequently used in aquaponics. We get the small 3/8 inch to quarter-inch size. Don’t use huge chunks! Lava rock is full of pores, that not only promote aeration and drainage, but are also the perfect habitat for beneficial microbes to grow. They don’t float to the soil surface like white bits of perlite do, and are generally more affordable than pumice.
3/8″ lava rock – added for aeration, drainage, moisture retention, and surface area for microbial life!
Our local landscape supply company carries volcanic rock both in bulk and in half cubic-foot bags. For any Central Coast locals, I am talking about AirVol Block in San Luis Obispo. This is where we get a lot of our hardscaping materials like stone blocks, green rock gravel, cobblestones, and pathway pavers too.
If you can’t find volcanic rock, pumice or perlite can totally be used! Availability of all these products will vary depending on your location.
Another thing that will help with aeration is… my favorite, worms!
Did you know that Cornell University refers to worms as “living soil amendments”? Worms play a vital role in the overall health of organic soil, as part of the soil food web. By simply being present and doing their wormy thing, they continually aerate, nourish, and improve soil structure! Furthermore, as they cruise through soil, they break it up – which in turn improves drainage, increases moisture retention and oxygen flow to plant root systems – all very good things!
“Worms feed on plant debris (dead roots, leaves, grasses, manure) and soil. Their digestive system concentrates the organic and mineral constituents in the food they eat, so their casts are richer in available nutrients than the soil around them. Nitrogen in the casts is readily available to plants. Worm bodies decompose rapidly, further contributing to the nitrogen content of soil.”
NSW Government Agriculture
Adding worms to raised garden beds
As worm castings are added into each of our raised beds, a few red wiggler compost worms (and their cocoons or babies) usually hitch a ride too! Now they’ve been introduced into the bed, and will continue to populate. Red wigglers are fairly small worms, reproduce quickly, and break down food matter fast, thus creating castings faster. They’re perfect in a worm bin, and good in the garden too! However, red wigglers generally like to stay near the soil surface. On the other hand, earthworms like European Nightcrawlers like to dive deeper in the soil to do all their good work. We add some of those big bad boys to our garden too!
European Nightcrawlers from Uncle Jim’s Worm Farm, about to to be added to the soil around our fruit trees – where the soil is compacted. A few got added to each bed too!
Please note: As strange as it sounds, most earthworms are not native species to North America. They are excellent additions to your garden, but some can disrupt native ecosystems (such as forests) if they’re introduced elsewhere. This is particularly a concern with a dense population of European nightcrawlers. Thus, please make responsible decisions when adding worms to your soil, depending on your garden (e.g. does it abutt a woodland?) Within the confines of urban or suburban gardens, their presence is welcome and helpful!
FILLING YOUR RAISED GARDEN BED
Now that we have a better idea of the types of materials we want to add to our raised beds, it is time to fill them up! Yep, our beds are 100% full of all this good stuff. Aside from sometimes adding bulk soil to the bottom of our deepest beds, there is no other “fillers” at the bottom. Just how the roots like it!
The goal is to get all of these materials evenly mixed, as much as possible. We’ll generally add them in “lasagna layers”, mixing as we go. For example, add several inches of bulk soil or bagged soil, a good layer of compost, a couple inches of volcanic rock, and mix. With that, the bed may only be about quarter full. Repeat with more layers of each, mix. Continue this process until the bed is full.
A “lasagna layer” of soil, compost, and volcanic rock. We’ll mix this up, and then add more of the same until it’s full!
On that note: try to fill your beds all the way up! They don’t need to be overflowing necessarily, but at least up to within a couple inches of the top. When you first water the bed, it will compact and sink down a little. Depending on how much it sinks, you may want to top it off with another layer of compost. We use compost on the top of our soil as mulch!
A post will be added later about mulching, but in a nutshell: Do it! Materials such as compost, leaves, straw, or pine needles can be used to top off a bed and increase moisture retention. Use what is most readily available and appealing to you!
A Note About Hugelkultur
To take up *some* space at the bottom of a deep empty bed, you could choose to add a few inches of small branches, leaves, mulch, pine needles, or other woody organic matter, and then add the other recommended raised bed soil and compost on top. The woody debris eventually break down and feed the soil as a carbon source over time. This follows a practice called Hugelkultur. However, I do not recommend adding non-organic matter such as rocks, plastic bottles or other random materials to take up space in your bed.
What about Fertilizer?
Most “virgin” soil will probably need some amending with mild, balanced, slow-release fertilizers to keep your plants healthy, happy, and productive! This is true whether it comes trucked in bulk or from a bag.
If you filled your raised garden bed primarily with high-quality organic bagged soils and compost, you can go pretty light on the fertilizer for the first growing season. Those bags usually contain pre-amended soil with light fertilizer and some compost added. But as the next growing season comes around, you’ll want to start implementing a fertilizer routine for your raised garden beds. As your plants grow, they will use up a lot of the available nutrients in the soil. If you fail to amend the beds in preparation for the new crops, you set them up to flounder and starve!
On the flip side, if you started primarily with bulk soil and compost from a local landscape company, you’ll most definitely want to add fertilizer from the start. That is, unless they say that it is already amended. Though I don’t think that is common practice for most bulk material.
Every gardener is going to have their own methods and opinions about fertilizers and amendments. Let me tell you about ours, and then you can make you own decisions and research further from there!
We don’t ever use the “heavy-hitter” fertilizers, like blood meal, bone meal, or feather meal. I call them heavy-hitters because they’re usually really high in one macronutrient or another – nitrogen, phosphorus, or potassium (NPK). While all those nutrients are essential, we don’t feel the need to dose our plants heavily with animal byproducts. Due to their strength, there is an increased risk for shocking and “burning” your plants. With all of the compost, worm castings, aerated compost tea, and other more natural, mild amendments and practices we use, we just don’t find the former to be necessary!
Let’s talk about what we DO use.
Instead of those “heavy hitters”, we prefer to add more mellow, balanced, slow-release, plant-based fertilizers to our raised bed soil. Down-To-Earth brand has been our go-to for the past several years, though we use other brands at times too. The main products we use are kelp meal, neem meal, alfalfa meal, or this vegan all-purpose fertilizer. They’re all OMRI-certified for organic gardening.
We sprinkle in these mellow meals on top of the soil, lightly scratching and working them in to the top few inches. We do this a couple times per year, usually between switching out crops in beds. Keep in mind we garden year-round here, so your fertilizing schedule may vary. I always suggest going a little lighter than the instructions on the box. You don’t want to accidentally “burn” the plants! Even these gentler options do pose some risk of that, if you overdo it. They all have their different benefits so we usually mix a few of them. If you were to start with just one, go for the all-purpose stuff.
Sprinkling in a combination of kelp, alfalfa and neem meals to the top of the soil once the raised bed is full. This will be scratched into the top few inches of the soil, and watered in. We also added some rock dust here, and earlier when the bed was only half-full.
One thing we always add to our garden is basalt rock dust. For brand-new raised beds, the wild areas of our yard with native soil, or when we are planting a tree. We consider this more of an amendment than a fertilizer. It is slow-release and cannot burn or harm plants like fertilizer can. Rock dust comes from volcanic ash. It is low in macronutrients, but absolutely loaded with trace minerals. It helps increase nutrient uptake by plants, increases crop yields, improves plant immunity, boosts pest resistance, and generally enhances soil and plant health. Check out Remineralize.org for more information and research about rock dust!
Another amendment we use in our raised bed soil is biochar. If you are curious to read more about biochar, see this post from Regeneration International.
There you have it!
Those are the kinds of things we add to our garden beds. When planting seedlings, we sprinkle mycorrhizae in their planting holes. Once the plants are established and growing, we routinely water with actively aerated compost tea (AACT and seaweed extract. However, this post is about FILLING a raised bed, not maintaining one.
Therefore, check out this article all about how we routinely amend and prepare our raised bed soil between planting seasons.
IMPROVING YOU EXISTING SOIL
Do you have raised beds that are already full of soil that you aren’t very happy with? Or more like, that your plants don’t seem very happy with? It’s okay! In fact, we have been in this boat before too. Do not feel the need to go dig out all your soil and start over. There is hope!
Before you consider replacing your raised bed soil, try amending it first using some of the materials we’ve discussed already. If your plants are sad and small, have you been fertilizing them adequately? Is your soil too compact? Try to mix in some aeration additive. Does it seem like the soil drains too quickly, or dries out to quickly? Add compost and worm castings! That, along with watering with aerated compost tea, will increase the microbial life in your soil. For better moisture retention, drainage, and “fluff”, peat moss or coco coir could also be mixed in. Note that coco coir is the more sustainable option of the two.
First, try those measures for a season and see if there is noticeable improvement. I really think there should be. If not? Next, consider taking out at least a portion of the old soil and replacing with the types of things discussed in this post.
The final full bed. Make sure to give it some water to get everything happy, and to get those microbes kicking!
And that is how we create our “perfect” organic raised bed soil.
I realize that if you are new to this world, this all may sound completely overwhelming! I get it, and I don’t mean to make you feel intimidated! The goal is simply to set you and your garden up for success!
Above all, if you had to take away just one message from this, it would be this: Compost compost compost, and worms worms worms! If you get those life-givers into your beds, the rest is simply an extra boost of kick-ass.
Thanks for reading. Feel free to ask questions, and spread the soil love by passing this along!
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One of the most popular questions I see from new gardeners is how to fill a new raised bed with soil. Many different methods are out there that work great! Everyone has different opinions and different materials available. I have researched a great deal to find how others have filled raised beds.
Here are the four best ways to fill a raised garden.
- Core Gardening
- Ruth Stout
- Back to Eden
Before we get started, if your raised bed has not been built yet, it may be good to take a look at our article Are Raised Garden Beds Better Than In-Ground Garden Beds?. This may help you decide which is the best option for your soil and climate.
Let’s get into the details of the best ways to fill a raised garden bed!
Calculate the Amount of Soil Needed
Before we get to the list, I think it is important to understand how much soil and organic material might be needed in order to fill a raised bed. Whether buying bags of material or buying in bulk by the yard, a little math is necessary to get a good estimate for how much is needed and what that might cost.
First, calculate the volume of the raised bed. This tells how much material the bed can hold.
Volume (cubic feet) = Length (feet) x Width (feet) x Height (feet)
Using a tape measure, measure the longest side of the bed, which is the length. Then, measure the shorter side, which is the width. Finally, measure the depth/height of the bed. If all of these measurements are in feet, the final volume answer will be in cubic feet.
For the sake of this article, let’s use an example of a raised garden bed that is four feet wide by eight feet long by one foot high. This is a pretty standard size garden bed. Our volume calculation would then be:
32 cubic feet = 8 L x 4 W x 1 H
It is normal to see bags of soil and compost in bags that are two cubic feet at garden stores. So thirty-two divided by two would mean that eighteen bags of material are necessary to fill this raised bed.
If the garden being filled is a large raised bed or multiple raised beds, it is probably a better deal to buy in bulk and get the material in cubic yards. In this case, divide the volume in cubic feet by twenty-seven in order to find out how many cubic yards of material is necessary. In our example, 32 divided by 27 equals about 1.18 cubic yards. So you would just buy 1 cubic yard of material.
I will reference some of these examples and methods for calculating the amount of material needed for a raised bed in the methods below.
1. Core Gardening
Photo credit to Luke at MIGardener from his video.
The concept of core gardening is to create an internal “sponge” down the middle of the garden bed. This core holds water like a sponge and will be able to wick moisture two feet in both directions.
Here are some of the benefits of the core gardening method:
- Less watering! Due to the core being able to hold water all season long, the garden will need to be watered much less (if at all depending on the climate). If mulch is kept on top of the soil, this will help with less watering even more!
- Fewer weeds! The surface of the soil can stay dry if the garden does not need watering very often. This means weed seeds have less of a chance of sprouting because they need water in order to germinate. Again, if the soil is kept mulched (as I ALWAYS recommend), weeds will most likely be smothered if they do happen to be able to sprout. This is just another benefit of covering gardens with mulch!
- Stronger root system for plants. Since the surface of the soil is dry, the roots of the plants will reach farther down into the soil for water provided by the core. This also helps the plants reach nutrients that are deeper into the soil and helps create a more healthy and strong plant.
- Reduces disease issues. Many disease issues are caused by too much moisture at the surface of the soil. By having the moisture for the plants be controlled by the core, the chances for fungus, mold, blight, and powdery mildew issues are greatly reduced.
Steps to create a core gardening raised bed.
These steps can be used whether you have an existing raised bed or you are filling up a new empty raised bed.
Build a trench for the core
Build a trench around 8-12 inches deep and about 1-2 feet down the middle of the raised bed. If an existing raised bed is being utilized, just push the soil to the sides or temporarily remove the soil.
For a new raised bed, first, I recommend putting cardboard or newspaper down for the base of the bed, assuming it is right on the ground. This will smother any grass or weeds that might exist. It is not even necessary to remove these weeds or grass first. Put some of the soil of choice (discussed later) on top of the cardboard/newspaper, but only a small amount depending on the height of the bed. Then, start the trench as mentioned above.
Fill the core of the raised bed
The core of the raised bed should be filled with wet organic matter that has already started to break down. The best and most recommended material to use is old straw bales. These can undoubtedly be found for free after Halloween! Just let them sit outside all winter to start breaking down before adding them to the core.
Other material that can be used in conjunction or in place of straw is old twigs, leaves or grass clippings. These items can be mixed together if they are all available. Either way, the core should be free to fill!
Fill up the core/trench with organic matter. Walk on top of the material to pack it down really well. I recommend shooting for about 4-5 inches thick of packed down material. It will be perfectly fine to have a slight mound down the center of the bed when it is finished because this will settle over time.
Charge the core!
Make sure to water the core thoroughly. This is referred to as “charging the core”. The whole purpose of the core gardening method is to create a sponge down the center of the bed that provides water to the plants all season long. Do not skip the step of watering the core!
Fill in the rest of the raised bed with soil
If an existing raised bed was being utilized, just fill back in the soil that was temporarily removed to create the trench for the core. Again, it is perfectly fine to have a slight mound down the middle. It will settle over time.
If a new raised bed is being filled, then decide on soil type and how much will be needed. Do not get really fancy with this. A 50/50 mixture of garden/topsoil and compost will do just fine for a raised bed.
Let’s use our example raised bed from above of 8 feet by 4 feet by 1 foot high. We said this was a total of 32 cubic feet. We have to estimate how much space our core might be using up because we can subtract this volume from how much soil we will need to fill in.
If our core is 2 feet wide by 8 feet long by 5 inches high, multiplying these numbers together (height converted to feet is 5 divided by 12 which equals .42) equals 6.6 cubic feet. I would recommend rounding this number down, causing you to get slightly more soil than you think you might need since the soil will settle over time.
So we had a total of 32 cubic feet of space in our raised bed and we filled up 6 cubic feet with soil, so we need 26 cubic feet of soil left to fill.
You can buy 7 bags of organic garden/topsoil and 7 bags of compost where each bag is 2 cubic feet in volume (so you would have 28 cubic feet). Depending on prices per area, this could reach a total of about $100. This may be too expensive for some gardeners.
It is possible to get this price down even cheaper! Try to find someone that has topsoil available for free, perhaps from a recent construction project. I also recommend working on making homemade compost to help reduce the cost, but this would obviously take time to produce.
Perhaps the best option is to buy the soil components in bulk. Topsoil and compost can be purchased by the yard. One yard is equal to twenty-seven cubic feet. In our example, we needed twenty-six cubic feet. The store may or may not sell topsoil and compost in half yards. If they only sell it by the yard, it will still more than likely be a less total cost than buying a half yard of bagged material, so essentially, two raised beds could be built for the price of one!
Supply some additional nutrients and plant!
Most likely, a new raised bed will need to be supplied with some additional nutrients. It would be good to find an organic granular fertilizer and perhaps a good nitrogen source such as manure or fish fertilizer. Keep your bed mulched at all times and add compost to the top of the soil every year and the need to purchase organic fertilizers should be eliminated in the future!
What should be done the next season?
After a year has passed, the core is most likely going to be gone. The organic material will have turned into great compost for the garden and the worms will be naturally tilling the garden.
Many people like to recreate the core year after year. Gardeners who build a trench again, fill in the organic matter, and charge the core are good to go for another year.
This probably works perfectly fine, and no doubt it is a better method than tilling the garden. However, I cannot get past the fact that the soil is being disturbed every year. Plus, it is extra work!
After the first or maybe the second year of implementing the core gardening method, I do not feel it is necessary to keep recreating it unless the garden happens to be in a very dry climate or the gardener just has no time to water, even infrequently.
If the soil is kept covered with mulch at all times and compost is added to the top of the soil each year, then healthy soil is definitely being built and the critical soil life below is not being disturbed. I feel it is not necessary for the extra work of creating a core each year in most cases.
2. Hugelkultur Raised Bed
Photo credit to Greg at MaritimeGardening from his video.
Hugelkultur is the process of burying large amounts of rotting debris under the soil. This usually includes large rotting logs, sticks and other debris.
As you may have noticed, the Hugelkultur method is very similar to the core gardening method. The benefits are almost identical, so I will not repeat them here in full detail.
A large sponge is still being created under the soil that holds water well and gives the plants nutrients. The roots of the plants will travel deeper into the soil to obtain the nutrients and water, which creates stronger plants.
One difference with this method is that the material underneath is much larger and will take a lot longer to decompose. This means it could last up to five years before that base sponge has turned into wonderful soil. While the material breaks down, it will heat up and create a microclimate under the plants and warm the soil, which can be useful in a colder climate.
Steps to create a Hugelkultur bed
The goal is to place rotting wood and other debris about 10-12 inches deep in the bed. If an existing raised bed is being used, dig out all the soil first. It may even be necessary to dig down deeper than ground level to get to this depth. Set the soil aside for now.
For a new raised bed, it is possible to save money later by digging into the existing topsoil and setting this aside. For our raised bed example above which is twelve inches deep, you may want to dig three to four inches of topsoil out. This will be three to four inches of soil you will not have to purchase later!
Now find old rotting logs, twigs, and other debris and throw them into the bottom of the raised bed. It is important that wood that is already starting to rot is being used, as this will hold water and provide nutrients to the plants much better than fresh wood.
Fill in all the extra space and gaps between the large logs with leaves, grass clippings, trimmings from bushes, wood chips, etc. This takes up space with free materials so it’s not necessary to spend as much money on filling up the bed.
Photo credit to Greg at MaritimeGardening from his video.
Water all the organic material
Next make sure all the logs, leaves, grass clippings, and the like are well watered, similar to the core gardening method above. This material will be the source of water for the plants above it all season long.
Fill in the rest of your raised bed with soil
Photo credit to Greg at MaritimeGardening from his video.
Ideally, a good amount of existing topsoil would have been dug out at the beginning of this process, so it may not be necessary to purchase much more. It may be a good idea to mix this topsoil with some bags of compost if more material is necessary to get your beds to full capacity.
Even if this garden was started with a brand new raised bed and three to four inches of topsoil was dug out, I don’t believe any additional soil will be necessary. If all of this topsoil is placed back on top of the rotting material, and then a few inches of mulch is added on top of the soil, this project should be virtually free!
Timing and final thoughts
This method may or not be right in any given situation depending on access to rotting logs and other material. But if these resources are available, then this can definitely be a free way to start a new garden bed or enhance an existing one!
This method can be constructed in the spring and the garden can be planted right away, or it can be started in the fall to allow the organic matter to break down all winter long and then the garden can be planted the following spring. The buried debris will feed the soil for about five years.
Again, it may be beneficial to use some organic fertilizer, manure, or fish fertilizer in the first year to jump-start the feeding of the soil in a new raised bed. However, if you follow our principles of adding compost to the top of the soil each year and keeping the soil mulched at all times, your need to purchase fertilizers in the future should be eliminated! No one fertilizes the soil in nature and everything grows just fine!
3. Ruth Stout Garden Bed
Photo credit to Greg at MaritimeGardening from his video.
Ruth Stout was a woman who was born in the United States in 1884 and nicknamed the “Mulch Queen”. She originally started gardening by tilling the ground every year, killing the soil life, and creating much more work for herself than there needed to be. Eventually, she discovered the power of mulch, particularly spoiled hay.
The Ruth Stout method promotes the use of mulching the garden with spoiled hay and building healthy soil quickly. Hay breaks down quickly, feeds the soil and reduces watering.
Now, keep in mind: hay tends to have an abundance of weed seeds! However, this method requires a thick layer of at least eight inches of hay at all times, and most weeds cannot germinate through this thick layer of mulch.
Starting a Ruth Stout garden bed is great to do in the fall in preparation for spring planting. However, if it is spring time, a Ruth Stout bed is a great way to start potatoes right away!
Steps to create a Ruth Stout garden bed
This method is probably the easiest to implement and the cost is very minimal assuming access to free hay.
A Ruth Stout garden bed should be built directly on the ground, but it is not required to have sides. However, I feel like having a standard garden bed with sides is a good idea just to keep everything contained – especially in windy areas.
Photo credit to Greg at MaritimeGardening from his video.
Start by adding a few inches of compost/aged manure right on top of the ground. It is not necessary to kill or remove any grass or weeds! Buy these products in bags as we discussed above or buy in bulk to save money. Any extra compost or manure can be saved to be used in another garden or used at a later time to add nutrients to this garden bed.
At this point, it is the perfect time to plant potatoes throughout this whole bed in the Spring! Do some research and buy seed potatoes that are suitable for your specific area. Do not cut the seed potatoes before planting. Just put the entire whole seed potato about halfway into the layer of compost/manure. If the potato is still visible on the surface, that is perfectly fine.
Now, spread the spoiled hay throughout the bed on top of the potatoes. The hay should be spread evenly and be eight to twelve inches deep. That is really all it takes to get this bed started! It is not necessary to water or touch this bed and a great potato harvest will occur!
This is a great method for getting a garden bed started for little to no money. It helps build soil fast, and in future seasons potatoes can be planted in the same way and more hay can be added, or other crops can be planted in the soil that has been built.
When planting other crops, the hay must be pushed to the side and the seeds/transplants be planted into the soil. As the plants grow, the hay can be pushed back around the plants as mulch.
This same concept for starting potatoes can be done with wood chips if hay is not easily accessible. We will talk more about wood chips in the next method!
4. Back to Eden Garden Bed
Photo credit to Gary at The Rusted Garden.
In your gardening research, you may have come across the term Back to Eden gardening. This approach has been made famous by Paul Gautschi. I highly recommend watching his film and videos on YouTube which you can find by simply searching for “Back to Eden Paul Gautschi”.
Paul did not invent or discover anything that didn’t already exist. Like Ruth Stout, after years of hard labor in the garden by tilling the ground, he discovered the power of covering the soil with mulch and mimicking nature and God’s design. Unlike Ruth Stout, he found great success with using free wood chips as his mulch of choice along with composted chicken manure.
The benefits of a Back to Eden garden are very similar to the other methods discussed above and these gardens can be started for very little cost. The wood chips help build healthy soil as they break down, provide nutrients to plants, reduce weeds, and hold the correct amount of moisture that plants need.
Steps to create a Back to Eden garden
Again, this method can be done with or without a raised garden frame. It is mostly recommended to start out a new bed by covering the ground with cardboard or newspaper. Wet this down so it smothers out all the grass and weeds.
Next, get some soil. Similar to the above methods, a 50/50 ratio of compost/aged manure and topsoil can be mixed and used. This might be available for free or it can be purchased by the bag or in bulk by the yard. A raised bed should be filled about halfway, or about six inches. To save some money, first, implement a subset of one of the first two methods above by putting some organic matter on top of the cardboard/newspaper.
On top of the soil is where the wood chips should be as the mulch layer. The wood chips can be as deep as desired, but generally about four inches or so would work well with the above method.
Wood chips should be able to be obtained for free by calling around to local landscaping and tree companies. They often get charged for dumping their wood chips at designated locations and would be more than happy to give their wood chips away for free. For those who are picky, wood chips created from a wood chipper are better than wood chips created from a wood shredder (both work fine!). A chipper will chop up the wood chips in a way that creates more surface area and will help the material break down faster. The way it lays together will also help prevent a suitable environment for slugs.
To save money, put wood chips right on top of the grass and weeds and don’t buy any extra soil. In this case, make sure the wood chips are piled at least eight inches deep.
In either case, do not ever mix the wood chips in with the soil. Also, never plant seeds or transplants in the wood chips. As with any mulch, always make sure to push back the wood chips and plant in the soil. The first few seasons, some organic fertilizer may need to be added, but over time, the wood chips will break down and create healthy and fertile soil for plants.
So that’s it! Those are four easy ways to start or enhance a raised garden bed. It all depends on which resources are available for free. Do not be afraid to ask around for these resources. Some cities have a free mulch and compost program. Farmers are also a great option for manure, straw, and hay. Wood chips and leaves should be the easiest resource to find from landscaping and tree companies or just on the side of the road from homes in the Fall.
This might be obvious, but each method is essentially the same thing – building soil with natural organic matter and always covering the soil with mulch. This is exactly how nature works! We just like to speed up the process a bit for our own gardening needs.
For he was looking forward to the city with foundations, whose architect and builder is God.
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This past week we made a raised bed and shared a timelapse of us building it and filling it. It went a bit nuts on social media and we had loads of people commenting on my technique of filling it.
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Time to fill the new bed.
I’ve filled my fair share of raised garden beds and I’ve got my technique down pat.
However when I made my first raised beds I made a rookie mistake. I bought the cheapest soil mix I could find just to fill the thing, I think I was paying $2 a bag from the cheap shops.
Everything I planted just basically turned yellow and died.
When ever I see people loaded up with a specific potting mix I want to run over to them an warn them.
The second time around, I went to the landscape suppliers and bought the best veggie patch mix you could get. I think we paid around $300 to fill two beds.
Same thing happened.
It took around 6 months with loads of other inputs for it to come good.
Now I want to share with you how I fill my raised bed so they are ready to roll.
My lasagne method
I use a method called the lasagne method, many people have very different techniques but I’ll share what I do which is layers of organic matter, compost and manure.
In the base if I am planting direct onto grass I’ll start with a layer of cardboard. If there are trees nearby I may also turn it into a wicking bed or use geofabric to stop them sucking the life out of the bed.
Then I will go around and do some garden pruning. I’ll pop all these pieces – the big branches in the bottom of the raised bed. For our garlic beds I used all my sunflower stalks.
From there I layer with home made compost, then a layer of cane sugar mulch, then a layer of manure, I keep layering with around 2 cm of each in depth with the final layer being well rotted compost. I add a little sprinkling of my goodie mix on top of the compost – just not the top layer. My goodie mix is my secret sauce and reserved for my dirt lover members but it’s basically a mix of trace elements to give the patch a boost.
The bottom layers of compost can be not quite ready. By the time your plant roots reach the base they should be all ready to go.
Want my exact step by step recipe for filling a raised bed? Get it here.
Of course the key to keeping the cost down is having access to home made compost and manure. I use a mix of well rotted chicken manure or horse manure from my hubbys uncles horses or my dad will bring me some sheep poo occasionally. Sometimes I’ll pay $2 for a bag of cow poo from some nearby hobby farms.
If you don’t have access to these things you can still do this method with commercial compost and manure. And to keep costs low you can use the cheaper compost mixed with the premium stuff. A good variety of brands is going to make sure your bed is well balanced.
If this is still out of your budget, take a look at straw bale gardening. This is a new method I’ve started using in areas where I want to build up new garden beds.
Want the step by step recipe for my raised bed method?
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Topsoil is the top layer of the earth’s surface. Topsoil is dark in color and high in organic matter, which makes it very easy to till and fertilize ground for growing plants. It is scraped from the ground and sold in bags or bulk, often called “black dirt”.
Where Can I Buy Topsoil?
Topsoil is widely available through a variety of sources, including garden centers, nurseries, and home improvement stores. Your topsoil should be screened; this means any extra materials — small rocks, roots, debris — have been removed. Topsoil is sold by the bag or in bulk. Bulk orders of topsoil are usually priced by the cubic yard, and the price varies based on location and availability.
Learn about soil amendments and nutrients.
Can I Use Topsoil in Containers?
You shouldn’t. Stick with potting soil for containers, and use topsoil in garden beds.
How do I Figure out how Much Topsoil I Need?
If you need to fill a raised bed or install a berm, you’ll probably want to use topsoil. You will need to measure the area’s square footage to calculate cubic feet. To fill a garden bed, you need at least 8 inches of depth of topsoil. New lawns will do best if you spread a layer of 3-6 inches of topsoil before planting.
Topsoil Myths & Misunderstandings
Veteran green thumbs probably know what works — regular amendments for soil, checking and remedying trouble spots — but for the rest of us, soil can present befuddlement and mystique. Here are four common misunderstandings about topsoil.
Topsoil Myth 1: All topsoil is pretty much the same. Topsoil can differ dramatically, even in the same yard and from one garden bed to another. All topsoil is made up of sand, silt, and clay in various proportions. When combined together in just-right proportions — 60 percent sand, 15 percent clay, and 25 percent silt — all those elements equal the best garden soil mix and an ideal growing environment for plants.
Topsoil also includes decomposed plant matter, called organic matter; that’s where plants get their nutrients. Good (and bad) insects and organisms such as earthworms live in the topsoil too, and you’ll also find air, water, and oxygen.
Learn how to evaluate your soil.
Topsoil Myth 2: If my soil is rich, I don’t have to fertilize. Every year, garden plants draw nutrients from the soil. Those nutrients need to be replenished for healthy garden plant growth. This is especially true for annual flowers and vegetables. Luckily, it’s easy and inexpensive to fertilize gardens with either granular or liquid products.
Topsoil Myth 3: I can use dirt from my yard for a new garden bed. You can, but in most cases, you probably shouldn’t. Soil includes varying amounts of decomposed plants, called organic matter. It’s the component that gives topsoil, or “black dirt,” good drainage and its loose, easy-to-till quality. Most soil around homes does not have nearly this much organic matter, which is why gardeners often buy topsoil to add to their garden or amend their soil with organic matter.
Purchasing topsoil is the easiest way to great garden soil. You can buy it in bulk or bags and put it directly on top of existing soil. For best results, put down a layer of 2-3 inches of topsoil, till it into the existing soil, then put the rest of the topsoil into your beds.
The other alternative is to amend soil by tilling in generous amounts of compost. This can be a lot of labor, and for best results should be repeated periodically, but ultimately it can create very productive soil.
Topsoil Myth 4: If I have good topsoil, I won’t have to till it. Soil can be become compacted, and it’s a good idea to till it whenever you get ready to plant annuals or vegetables. Even better, add 1-2 inches of compost while you’re tilling to keep the soil as rich and loose as possible.
improve your soil
- By Kelly Roberson
Topsoil calculator for raised beds: topsoil calculator metrics made easy
Using topsoil to enhance your beds can promote the healthy growth of a wider range of flowers without synthetic fertilisers. However understanding the types and quantities needed to boost growth is vital to achieving the right balance of topsoil. Luckily, our topsoil calculator helps you assess the ideal quantity you need for your project.
Our innovative topsoil calculator lets you measure the volume of topsoil needed according to the dimensions of your plot, thereby ensuring value for money: though topsoil keeps, you want to make sure you aren’t ordering far more than you need.
To asses exactly how much topsoil you need, visit the page for our topsoil calculator. For raised beds, simply measure the dimensions of your bed and enter the relevant information into the fields to get a precise measure of how much you need.
Contact our team on 0871 971 0988 to learn more about the benefits of using our topsoil calculator for raised beds, allotments, borders and other planting spaces.
how much soil i need for a 4×4 raised bed
Hello xdhunter and welcome to the The Community. We are glad that you are here.
The table below shows how much garden soil you will need to purchase to fill a 4 ft x 4 ft raised bed. The “deeper” the raised bed, the more soil you will need. Remember that the plants that you are planting will also take up space in the raised bed. The soil quantities shown are approximate.
For best results, incorporate 20-30% soil amendment, manure, or compost into your mixture – your plants will love it! Adjust the soil quantity accordingly. Most bagged goods are sold as 1 cu ft or 2 cu ft in the Outside Garden Department at your local Home Depot store.
Some soils include fertilizer, however you may need to apply additional fertilizer (slow-release granular or water soluble) depending upon your plants.
Over time, the soil may become compact and you will want to add additional soil. You will definitely want to “turn” the soil to aerate it before the next growing season; you will add more soil at that time.
Best wishes on your project.